Microcellular Injection Molded Wood Fiber-PP Composites: Part II - Effect of Wood Fiber Length and Content on Cell Morphology and Physico-mechanical Properties

Abstract

Microcellular wood fiber reinforced PP composites, a new development using bio-fiber strengthened plastic, are prepared in an injection molding process. The microcellular composites with five different types of wood fibers (hard wood fiber, finer hard wood fiber, soft wood fiber, finer soft wood fiber, and long wood fiber) are examined. The influence of wood fiber content (30-60% by weight) on the microcellular properties is also investigated. Microcell morphology (cell size, shape, and distribution) is observed using optical light and scanning electron micrographs (SEMs). The wood fiber length, geometry, and content strongly affected the microcellular structures of wood-PP composites. Composites with finer wood fibers possess better microcellular structures, and at a constant chemical foaming content, the higher percentage of wood fiber results in composites with smaller microcells. Due to the finer microcellular structures, finer wood fibers also result in improved physico-mechanical properties.